Store/retrieve data in *.rtm files - how?

rbuser

Hi,
is there a chance to store some constants/string variables in *.rtm
files?

I'd like to extract that data after loading the template with
"LoadfromFile" and store the data before doing the "Save".

Regards
Bernd

nardmoseley

-----------------------------------------------------
Tech Tip: Storing Custom Information with Templates
-----------------------------------------------------

Question:
---------

How can I store descriptive information with my report template?


Solution:
---------

1. If you are storing the templates to a database, then you can use the
Report.Template.OnSaveEnd and OnLoadEnd events to store and load the custom
information to appropriate data fields for the record. (This is the
technique used by the ReportExplorer.)

2. If you are storing templates to .rtm files, then you will need to store
the custom information in an Offset area of the template file. The
Report.Template object enables you do this by utilizing the Template.Offset
property and the Template.OnLoadStart and OnLoadEnd events. Below is a
detailed example.



Example:
--------
- Create a new application.
- Add to the main form one TButton, one TppReport and one TppDesigner.
- Set the Designer's Report property to ppReport1.
- Add ppTypes to the uses clause.


type
TForm1 = class(TForm)
Button1: TButton;
ppReport1: TppReport;
ppDesigner1: TppDesigner;
procedure FormCreate(Sender: TObject);
procedure Button1Click(Sender: TObject);
private
procedure LoadReportStreamEvent(Sender: TObject; Stream: TStream);
procedure SaveReportStreamEvent(Sender: TObject; Stream: TStream);

public

end; { class TForm1 }


{note: use compiler directive to declare strings as 'ShortStrings'
this is required for record structures}

{$H-}

{record structure used to store information inside report template }
TmyTemplateInfo = record
HeaderID: Integer;
Comments: String;
DateTime: TDateTime;

end; {record, TppTemplateRec}

{$H+}


const
cHeaderID = 12345;

implementation


{-------------------------------------------------}
{ TForm1.FormCreate }

procedure TForm1.FormCreate(Sender: TObject);
begin

{setup Template events }
ppReport1.Template.Format := ftASCII;
ppReport1.Template.Offset := SizeOf(TmyTemplateInfo);
ppReport1.Template.OnLoadStart := LoadReportStreamEvent;
ppReport1.Template.OnSaveEnd := SaveReportStreamEvent;

end; {procedure, FormCreate}

{-------------------------------------------------}
{ TForm1.Button1Click }

procedure TForm1.Button1Click(Sender: TObject);
begin

ppDesigner1.Show;

end; {procedure, Button1Click}

{--------------------------------------------------}
{ TForm1.LoadReportStreamEvent }

procedure TForm1.LoadReportStreamEvent(Sender: TObject; Stream: TStream);
var
lTemplateInfo: TmyTemplateInfo;
lsMessage: String;

begin

{read string stored in template header }
Stream.Seek(0, soFromBeginning);
Stream.Read(lTemplateInfo, SizeOf(TmyTemplateInfo));

{note: if not one of the templates with our header info, then set Offset
to 0 }
if lTemplateInfo.HeaderID = cHeaderID then
begin
lsMessage := 'Reading data from template file: ' + #13#10 + #13#10 +
lTemplateInfo.Comments + ' (' +
DateTimeToStr(lTemplateInfo.DateTime) + ')';

MessageDlg(lsMessage, mtInformation, [mbOK],0);
ppReport1.Template.Offset := SizeOf(TmyTemplateInfo);
end
else
ppReport1.Template.Offset := 0;

end; {procedure, LoadReportStreamEvent}


{------------------------------------------------------------------------------}
{ TForm1.SaveReportStreamEvent }

procedure TForm1.SaveReportStreamEvent(Sender: TObject; Stream: TStream);
var
lTemplateInfo: TmyTemplateInfo;
lsMessage: String;

begin

lTemplateInfo.HeaderID := cHeaderID;
lTemplateInfo.Comments := 'This comment is being stored inside the report
template, ' + #13#10 +
'along with the date and time written. ';
lTemplateInfo.DateTime := Now;

{write info to template header}
Stream.Seek(0, soFromBeginning);
Stream.Write(lTemplateInfo, SizeOf(TmyTemplateInfo));

lsMessage := 'Writing data to template file: ' + #13#10 + #13#10 +
lTemplateInfo.Comments + ' (' +
DateTimeToStr(lTemplateInfo.DateTime) + ')';
MessageDlg(lsMessage, mtInformation, [mbOK],0);

end; {procedure, SaveReportStreamEvent}








--
Nard Moseley
Digital Metaphors Corporation
http://www.digital-metaphors.com